1. Field of the Invention
The present invention relates to an Internet Protocol version 6 (IPv6) based Lower Power Wireless Personal Area Network (LoWPAN). More particularly, the present invention relates to supporting mobility for LoWPAN and a system for IPv6-based LoWPAN.
2. Description of the Related Art
A low power wireless network, particularly, a low power Wireless Personal Area Network (LoWPAN), is a simple low cost communication network that allows for wireless connectivity in application with limited power and relaxed throughput requirements. Wireless sensor network such as ZigBee, which is a non-IP network, is an exemplary LoWPAN, and there have been continuing research and standardization efforts in the IPv6 over LoWPAN (6LoWPAN) for providing IP network connectivity to non-IP based LoWPAN by means of a gateway. However, there are many problems which remain unsolved that hinder the implementation of the 6LoWPAN. One of the significant problems is a mismatch in transmit unit size between IPv6 and IEEE standards.
For example, IPv6 packet has a Maximum Transmission Unit (MTU) of 1280 bytes, whereas Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 standard packet is only allowed to carry an 81-byte Protocol Data Unit (PDU) for upper layers. Thus, the IEEE 802.15.4 packet is very short in comparison with the IPv6 MTU. That is, the Media Access Control (MAC) layer packet can vary up to 127 bytes. In consideration of a MAC header in which maximum length is 25 bytes, the MAC layer packet spares only 102 bytes for upper layer payload. Furthermore, an optional but highly recommended security feature at the link layer poses an additional overhead, leaving only 81 bytes.
In order to solve the aforementioned packet size mismatch problem, an adaptation mechanism has been proposed for fragmenting and reassembling IP packets between the IP layer and LoWPAN MAC layer. The adaptation layer is responsible for fragmentation, reassembly, IPv6 header compression/decompression, User Datagram Protocol/Transmission Control Protocol/Internet Control Message Protocol version 6 (UDP/TCP/ICMPv6) header compression, mesh routing, and IPv6 address autoconfiguration.
Meanwhile, there are increasing needs for providing Internet access services to mobile nodes, as well as for fixed nodes or networks. However, the conventional 6LoWPAN packet is limited to support mobility to the mobile nodes and networks, due to the lack of its inefficient design and packet length limit in the mobility header.
Accordingly, there has been a long-felt need in the art to develop a method for compressing the LoWPAN packet for supporting mobility to the LoWPAN while improving transmission efficiency of the IPv6 packets.